Light-emitting diodes ("LEDs") and other optoelectronic devices are ubiquitous in the modern electronics industry. Hundreds of millions of LEDs are produced annually by highly automated processes. LED lamp production begins with the manufacture of an "endless" strip of leadframes, which is cut to yield individual pairs of cathode and anode leads. Each cathode lead is affixed with a light-emitting diode, and the LED and anode lead are connected with a conductive wire. The assembly is then potted in a transparent thermosetting material.
LED leadframes are typically manufactured by a stamping and plating process. A strip of copper or mild steel metal is stamped into the form of a plurality of anode and cathode leads having a desired shape, connected by an integral frame. The metal strip is then plated with a bondable metal to provide electrical leads with a highly conductive surface. Silver is the material of choice for both die attachment and wire bonding in the final assembly of LED lamps. Once plated, the leadframe is cut to a manageable length and used in the assembly of LEDs and other optoelectronic devices.
The cost of traditional leadframe production depends primarily, and in an approximately equal amount, on the steps of stamping the metal strip and silver-plating the stamped strip. Average leadframe cost is approximately $10 per thousand. Given the heavy demand for LEDs, even a slight decrease in leadframe unit cost translates into a tremendous overall cost savings. Accordingly, a method of leadframe production that avoids both stamping and silver-plating would be of great benefit to the electronics industry and, ultimately, consumers.
A related drawback of traditional leadframe production is the large amount of scrap metal that results from the stamping of metal strips into leadframes. A process for leadframe production which avoids the stamping technique would be both financially and ecologically advantageous.